Health care workers routinely risk exposure to communicable diseases through accidental exposure to contaminated medical products, waste products and bodily fluids. One of the largest exposure risks to healthcare workers and handlers of related hazardous waste is from accidental needlesticks or scratches from used hypodermic syringes. The Centers for Disease Control and Prevention reports that there are in excess of one-half million reported accidental needlesticks each year and an estimated three million additional needlesticks not reported. It is further reported that the odds of a healthcare worker contracting human immunodeficiency virus (HIV) alone through a needlestick are one in 300. The odds of a healthcare worker contracting any of many other serious or potentially fatal diseases such as hepatitis are even greater. In response to this health issue some states are enacting legislation requiring exclusive use of safety hypodermic syringes with retractable or protected needles.
Numerous solutions to the needlestick problem have been proposed, including U.S. Pat. No. 4,790,822, which discloses a disposable syringe in which the needle can be captured by a plunger and then fully retracted into the barrel of the syringe. The plunger shaft may then be broken off flush with the end of the barrel such that the needle may not be mechanically projected to extend beyond the opposite end of the barrel.
U.S. Pat. No. 4,747,830 discloses a similar system including a plunger that can be broken off once the needle is fully retracted into the barrel of the plunger. U.S. Pat. Nos. 4,692,156 and 4,675,005 both disclose disposable syringes wherein the needle can be fully retracted into the barrel of the plunger. U.S. Pat. No. 4,643,200 discloses a similar system used with a blood donor assembly, which allows retraction of a needle into a barrel.
U.S. Pat. No. 4,425,120 discloses a movable needle guard conduit which extends from the barrel of the syringe over the full length of the needle. The needle guard may be retracted during use of the syringe and may then re-extend to cover the needle following use of the syringe. U.S. Pat. No. 4,816,022 discloses a syringe with a sliding cap which utilizes a nub and backseat for engagement of a nosepiece for securing the cap around the syringe. U.S. Pat. No. 3,008,570 discloses a removable cap for enclosing and protecting a sterilized syringe in a moveable housing.
U.S. Pat. No. 5,000,736 discloses a syringe including a tubular plunger from which air has been evacuated which upon use may retract the needle into the plunger by differential pressure. U.S. Pat. No. 5,885,257 discloses a syringe which utilizes a compressed spring placed between a needle carrier and the barrel of the syringe and including a releasable retaining means to hold the needle carrier in position until retraction is desired. U.S. Pat. No. 4,908,022 discloses a disposable safety syringe including a cylinder which is pre-filled with fluid medication, a double ended needle and a plunger. Following use of the syringe, the end of the needle which extends into the barrel may penetrate the piston such that the needle may be manually withdrawn into the barrel by axial retraction of the plunger which remains in engagement with the needle.
Thus, a variety of prior art retractable syringes are known. Prior art syringes, however, have not offered a universally acceptable solution to the needlestick issue.
Healthcare workers throughout the world may benefit from a syringe which reduces or eliminates the risk of accidental needlestick or exposure to contaminated surfaces such as the exterior surface of a used needle, by overcoming the disadvantages of prior art syringes. An improved syringe is desired which is simple in design, manufacturing and operation so as to be widely applicable, cost effective, reliable and which does not require pre-filling with medication or fabricating with stored potential energy. A syringe is also desired which may become an industry standard through overcoming the disadvantages of prior art.
The disadvantages of the prior art are overcome by the present invention and an improved retractable needle syringe is hereinafter disclosed which has particular utility in protecting healthcare and sanitation workers.